华南暖区暴雨预报的模式初始场质量敏感性分析

Sensitivity analysis of model initial value of a rainstorm in the warm sector of South China

本文利用高分辨率中尺度数值预报模式WRF和两组再分析资料,在研究不同模式初值对华南暖区暴雨预报质量差异明显的基础上,利用合成初值方法进行了模式初值对暖区暴雨预报的敏感性数值试验研究,讨论了模式初始场关键物理量对暖区暴雨预报质量的影响,重点开展了模式初值湿度场质量对华南暖区暴雨降水预报的敏感性分析。结果表明:模式初始场质量的较小差异,可显著影响本次华南暖区暴雨预报的降水强度、降水落区以及降水发生时间等的质量。初始水汽场对暖区暴雨预报影响最大,也最为敏感,是准确预报对流单体的发生发展以及地面强降水的基础。风场和温度场对暖区暴雨预报的影响相对较小。对流层低层较强的风速辐合是本次暖区暴雨强对流单体触发、生成和加强发展以至产生暖区强降水的物理基础。

Based on the high-resolution mesoscale numerical prediction model WRF and two reanalysis data,the sensitivity of the initial model values to the rainstorm forecast in the warm sector of South China was studied by using the combined initial value method.The influence of the key physical variables of model initial fields on the rainstorm forecast quality in warm sector was discussed.The sensitivity analysis of the initial humidity field quality to the rainstorm forecast in warm sector of South China is emphasized.The experimental results show that the small difference in the initial field quality of the numerical prediction model can significantly affect the quality of precipitation intensity,precipitation area and precipitation occurrence time of the rainstorm forecast in the warm sector of South China.The initial water vapor field has the greatest influence on the rainstorm forecast in the warm sector and is the most sensitive,which is the basis for the accurate prediction of the occurrence and development of convective cell and heavy precipitation.The influence of wind fields and temperature fields on rainstorm forecast in warm sector is relatively small.The strong convergence of wind speed in the lower troposphere is the physical basis for triggering,generating and strengthening of the strong convective cell,and even producing the heavy precipitation in the warm sector.